The present invention claims priority to Japanese Patent Application No. P2000-301410 filed on Sep. 29, 2000. The above-referenced Japanese Patent Document is hereby incorporated by reference to the extent permitted by law.
The present invention relates to a method for the preparation of a fuel cell. More particularly, it relates to a method for the preparation of a fuel cell employing a carbonaceous material for a fuel electrode and/or an oxygen electrode.
As the world""s supply of fossil fuels is limited, there has been ongoing research directed toward alternative energy sources, including those that may be more environmentally friendly than traditional fossil fuels. A hydrogen gas fuel is one such example. Since hydrogen contains relatively large amounts of energy per unit weight and because it does not emit noxious gases or gases contributing to global warming, hydrogen may be an ideal energy source that is clean and moreover plentiful in supply.
Fuel cell technology involves the recovery of electrical energy from hydrogen. Fuel cell research is proceeding rapidly, with a variety of promising applications, such as large scale power generation, on-site self-generation of power, or as a power source for electric vehicles.
The fuel cell includes a fuel electrode, such as a hydrogen electrode, and an oxygen electrode, arranged on both sides of a proton conductor film. Supplying fuel (hydrogen) and oxygen to these electrodes induces a cell reaction that develops an electromotive force. In preparing the fuel cell, the proton conductor film, the fuel electrode and the oxygen electrode are routinely molded separately and bonded together.
However, in forming the fuel electrode and the oxygen electrode separately, a variety of inconveniences arise due to difficulties encountered in handling. For example, if the strength of the fuel electrode or the oxygen electrode is considered, a certain thickness is needed (e.g., a thickness on the order of 100 xcexcm or more). However, if the electrode thickness is increased, the efficiency of the cell reaction is lowered, thus lowering cell performance. If, in order to avoid this, the electrode thickness is decreased, the electrolyte film (or like film) cannot be handled as an independent film, thus significantly lowering production yield.
The production process associated with molding an electrode material and bonding it to a proton conductor is extremely cumbersome and inefficient in view of productivity.
The present invention provides a method for the preparation of a fuel cell that is capable of producing superior cell performance. The present inventors have found that, by placing a proton conductor in an arc discharge space, an electrode composed of a carbonaceous material can directly be formed on the proton conductor.
In an embodiment, the present invention relates to a method for the preparation of a fuel cell producing arc discharge across carbonaceous electrodes to deposit the generated carbonaceous material directly on the proton conductor for use as a fuel electrode and/or as an oxygen electrode.
In an embodiment, because carbonaceous material generated by arc discharge is directly deposited on the proton conductor as a support to form the electrodes, it is unnecessary to handle the fuel and oxygen electrodes separately, and thus it is unnecessary to consider mechanical strength. Accordingly, these electrodes can be reduced in thickness, thus the cell reaction proceeds smoothly to improve cell performance.
The operation of separately preparing the fuel or oxygen electrodes and bonding the electrodes to the proton conductor is unnecessary to improve the productivity appreciably. In an embodiment of the present invention, since there is no necessity for separately handling the fuel or oxygen electrodes, complex operations are unnecessary and the production yield can be improved appreciably. Additionally, since the mechanical strength of the fuel or oxygen electrodes is if minimal importance, electrodes having superior cell characteristics such as energy density can be produced.
Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the figures.